1. Field of the Invention
The present invention relates to a lens barrel including an extender.
2. Description of the Related Art
Previously, as a lens apparatus (a lens barrel) that is used for a television camera such as an ENG camera, a zoom lens apparatus including an extender is used. The extender inserts a magnification-varying lens into an optical path of an image pickup optical system or retracts it from the optical path so as to change a magnification of an image. The operation of insertion or retraction of the magnification-varying lens is performed by a user to perform a rotating operation of an operating lever that is an electric remote controller or that is provided on a casing (an exterior frame) of the extender.
Japanese Patent Laid-Open No. 2005-351926 discloses an extender apparatus that is configured so that insertion or retraction of the magnification-varying lens with respect to an optical axis is performed by a one-touch operation.
However, the extender apparatus that is disclosed in Japanese Patent Laid-Open No. 2005-351926 is unitized and is built between lens units that constitute a main optical system of the lens barrel. Therefore, when an exterior part to which a zoom ring, a focus ring, an AF switch, an IS switch, or the like is attached needs to be changed in maintenance, the lens units that constitute the main optical system, as well as the extender apparatus, has to be removed. In this configuration, the performance of the main optical system is varied in changing the exterior part, which is not preferable in view of maintainability.